The present invention relates to signs in general and to illuminated traffic highway signs, in particular, that meet the requirements of traffic highway design and traffic highway intersection design, signing signaling to improve safety and traffic flow on highways and highway intersections.
Traffic signs, such as STOP signs, are not typically directly illuminated. Any illumination they get comes from indirect exterior light sources, such as street lights, vehicle headlights and other sources. The levels of illumination impinging on the signs would be highly variable at each location, with some signs receiving more than adequate illumination and other signs receiving minimal lighting, since street lights are generally provided for general illumination.
For traffic signs located in remote areas where utility power is not readily available, street lights would not generally be available to illuminate the traffic signs. In these areas, the traffic signs would only be illuminated by the vehicle headlights, which could be inadequate. For example, where the traffic sign is obscured by a blind curve, the sign would not be lit until the driver is almost in front of it. This may not provide the driver sufficient time to react safely.
There is, therefore, a need to have an illuminated traffic sign that is visible to a driver before the vehicle""s headlights hit it without depending on ambient lighting sources for illumination.
The present invention provides a traffic sign that allows illumination of the sign without extensive maintenance costs and provides for identical appearance of the sign when both lit and unlit, while meeting the design code specifications required by the U.S. Transportation Department of regulatory highway signing set forth in the U.S. Department of Transportation Federal Highway Administration (FHWA) regulations, including NCHRP 350, Manual of Uniform Traffic Control Devices (MUTCD), the American Association of State Highway and Transportation Officials (AASHTO) or other design codes.
It is therefore an object of the present invention to provide an illuminated traffic sign that meets the various design code and regulatory restrictions while avoiding the disadvantages of the prior art.
It is another object of the present invention to provide a traffic sign that meets MUTCD requirements both when not illuminated and also when illuminated.
It is still another object of the present invention to provide a reflective sign which when illuminated either by an interior light source in accordance with the present invention or by an exterior light source, such as a car headlight, will appear the same to the driver, thereby avoiding confusion for the driving public.
It is a further object of the present invention to provide an illuminated sign which is easily seen at night before the sign""s retro-reflective properties are activated by an exterior light source, such as a car""s headlights as a car travels around a curve approaching an intersection, since a retro-reflective sign is only visible at night if a car is heading directly at the intersection.
It is another object of the present invention to provide a sign, such as STOP sign, which remains visible at night after an exterior light source is removed from shining directly at the sign. For example, a driver of an automobile can easily see the prior art STOP sign while the headlights are pointed at the sign, but as the car gets closer to the intersection the car""s headlight will no longer shine directly on the STOP sign, throwing the sign into darkness.
It is still another object of the present invention to provide a relatively low cost and easy to maintain means of upgrading highway and intersection safety without the cost of exterior sign illumination equipment and/or traffic light signaling equipment.
In summary, the present invention provides a traffic sign illuminated by an interior electroluminescent lamp that meets the federal requirements for traffic signing when the sign is lit or unlit. The lamp may be activated by the vehicle""s headlights and/or by radar detection and/or other such means. Utility or solar power, with battery backup, ensures reliable operation for the lamp.
The present invention provides an illuminated sign, comprising a sign panel; a light source disposed to illuminate the sign panel; a power source operably connected to the light source; and first and second switches connected in series between the power source and the light source such that the light source is activated only when the first and second switches are ON, wherein the first switch is turned ON by an approaching vehicle and the second switch is turned ON during daytime.
These and other objects of the present invention will become apparent from the following detailed description.